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Posted: 2/24/2004 2:16:44 PM EDT
| I decided to look at a handfull of my spent brass the other day at the range and noticed that the bases are slightly chewed up. My rifle is a Bushmaster V-match 16" and is fairly new <1000 rounds. The ammo was IMI M855 Lot 207D, 2002 manufacture. I also noticed earlier that the extracted casings are striking the deflector with such force that it has chipped some of the finish off down to the bare metal. I tried to take some close-ups, but the macro feature on my camera doesn't work well. I was wondering if my rifle is extracting too forcefully, or is it something else? |
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An extractor MARK is normal on the case rim. If you're getting rim deformation, you have other issues. Some possibilities are: Extractor not seating deep into the case rim, thus extraction force is all on the edge of the rim. Had this one myself with a DPMS bolt, inspect your case rims closely. Tight or rough chamber. Chamber should be chrome-lined on the BM. Too large of a gas port allowing a lot of gas through early, thus causing extraction to start early while the residual case pressure is still high and holding the casing firmly to the chamber walls. This could be further exaccerbated by a weak buffer spring. Short headspace. Has headspace been verified with GO and FIELD guages? |
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I see what look like normal extractor and ejector marks for a 16" AR. Your extractor may have a slight burr on it, but not much. That IMI ammo is a full boat 5.56 loading, and as hot as you will find. Try some Winchester white box or other commercial 223 loadings and see if the ejection is somewhat milder. |
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Quoted: I barrowed a good camera and took a picture of the case rims. Every one that I looked at had identicle marks like this: [url]http://www.hunt101.com/data/500/11727spentshells.JPG[/url] I thought you were talking about the other side of the case rim where the extractor lip fits into. Now I see you were worrying about nothing! [:)] |
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